New York: Bell Telephone Laboratories 1950. First Separate Edition. 4to., pp. 14; original printed wrappers; ex-library stamp (dated Nov 21, 1950); perforations for ring binder as issued; very good. Small scratch to upper left corner near second hole punch. First separate issue, October 1950. Originally published in the Bell System Technical Journal Vol. 29, pp. 147-160, April 1950. The Bell Telephone System Monograph series was primarily distributed to libraries that subscribed to the series. Very Good. Stapled wraps. 
First printed in the April 1950 issue of the Bell System Technical Journal, this Monograph was issued October 1950. Often erroneously referred to as offprints, the Monograph series was not published in most cases contemporaneously with the original publications (this is an exception). The series also included work by Bell System employees that were first published outside the Bell System umbrella. They are, however, usually the first separate publication, and are thus highly prized by collectors since offprints in the traditional sense were not produced in the Bell System as far as we are aware.
"Hamming was the first coding theorist to attract widespread interest in his work...frustrated when a failure in one of Bell Lab's relay comptuers had spoiled a run of data, Hamming began deveooping the first error-correction codes (now known as Hamming codes), which enabled computers to find and correct single errors in a stretch of data, as well as to discover double errors. Error correction has since been developed into a scientific discipline..." (Origins of Cyberspace 646)